Compensating sheave for elevators



Sept. 8, 1942. E. M. BOUTON COMPENSA'I'LNG SHEA V135 FOR ELEVATORS Filed May 15, 1941 3 Sheets-Sheet 1 INV ENTOR Edgar/14500190.

WITNESSES: a?

A ORNEY Sept. 8, 1942. E. M. BOUTON COMPENSATING SHEAVES FOR ELEVATORS Filed May 15, 1941 5 Shgaets-Sheet 2 INVENTOR Edgar W. Bod/0x7.

WITNESSES: 2 z

WW' M ATTO NEY Sept. 8, 1942- E. M. BOUTON 2,295,381

COMPENSATING SHEAVES FOR ELEVATORS Filed May 15, 1941 3 Sheets-Sheet 3 Patented Sept. 8, 1942 COMPENSATING SHEAVE FOR ELEVATORS Edgar M. Bouton, Nutley, N. J., assignor to Westinghouse Electric Elevator Company, Jersey City, N. J a corporation of Illinois Application May 1 5, 1941, Serial No. 393,546

6 Claims. (Cl. 187-22) My invention relates to compensating sheaves for elevators and more particularly to mechanism for controlling the vertical movements of compensating sheaves.

In the operation of elevator cars provided with counterweights and compensating sheaves, it may happen that the safety brake is applied to a car with such force as to cause it to decelerate at a much greater rate than the gravity rate at which the counterweight normally decelerates. In such an instance this difference between the rate of deceleration of the car and the counterweight applies a force to the compensating cables .to raise the compensating sheave. Where a lockdown compensator such as is illustrated in I-Ialfvarson Patent No. 1,976,494 of October 9, 1934, is used, the upward movement of the compensator sheave is restrained, tying the mass of the counterweight and other moving parts to the car to prevent excessive car retardation. This places a strain on the compensating cables which, if excessive, may damage them.

It may happen that the counterweight will continue its upward run after the car has been stopped against its humper or buflfer in the pit, thus causing the compensating cables to apply an upwardly directed force to the compensating sheave. In cases of this nature where the upwardly directed force against the lock-down compensating sheave becomes excessive, it is likely to cause serious damage to the cables or other parts of the elevator system.

One object of my invention is to provide a compensating sheave mechanism which will permit the normal expansion and contraction of the hoisting and compensating cables of the elevator while preventing any development of slack in the cables and which will so control the sheave that it will offer a predetermined resistance to a continued rise of the cables after they rise beyond a predetermined distance.

Another object is to provide a compensating sheave mechanism which will cause the compensating sheave and cables to exert a braking action on the counterweight when the car has been stopped against its bumper in the pit and the counterweight continues its upward movement.

A further object is to provide a compensating sheave mechanism which will so control the compensating sheave as to avoid breakage of the compensating cables when they are subjected to excessive strains.

It is also an object to provide a compensating sheave mechanism which will permit the sheave to move upwardly beyond its highest normal 55 rails compensating position when the compensating cables apply an upwardly directed force beyond a predetermined value and at the same time to apply a, predetermined braking effect to further upward movement of the sheave after it moves above its normal compensating position.

An additional object is to provide a compensating sheave mechanism which will permit the compensating sheave to freely move upwardly a predetermined distance and, when it is forced beyond such distance, to provide a predetermined resistance or braking effect against such further movement.

For a better understanding of my invention, reference may be had to the accompanying drawings, in which:

Figure 1 is a View in side elevation of my improved compensating sheave unit.

Fig. 2 is a View in front elevation of the sheave unit shown in Fig. 1.

Fig. 3 is a top plan View thereof, and

Fig. 4 is a top plan view of the rail gripping jaws embodied in the unit.

Referring more particularly to the drawings, I have illustrated a compensating sheave mechanism comprising a cable receiving sheave I which hangs in the lower loop of a plurality of compensating cables 2 near the bottom of a hatchway (not shown). The hub of the sheave I is provided with roller bearings 3 secured by retaining rings 4 through which a shaft 5 is disposed to support a weight frame 6. The frame 6 comprises a pair of heavy side plates 1 and 8 joined together by suitable bolts 9. Each side plate is provided with a bearing III for receiving the ends of the shaft 5. A pair of setscrews I I are mounted in the lower part of the bearings for locking the shaft therein.

A plurality of guide shoes I4 extend laterally from the upper and the lower ends of the side plates into cooperative engagement with a pair of guide rails l5 and I6, the lower ends of which may be secured in the bottom of the hatchway in any suitable manner. The sheave I is free to rotate on its roller bearings 3 within the weight frame 6 which is restrained from rotation by the vertical guide rails I5 and I6.

Inasmuch as the weight frame 6 is supported on the sheave, which,'in turn, is supported in the lower loop of the compensating cables, the weight of the frame and the sheave tensions the cables to continuously permit normal expansion and. contraction thereof because the frame may move freely up and down between the vertical guide I5 and I6. If desired, suitable weights may be added to the side plates to increase the tension on the compensating cables.

A pair of rail-gripping jaws l9 and 20 hinged together by a bolt 2|, are clamped to the guide rail l by a bolt 24 which extends through suitable openings in the central portions of the jaws, as shown in Figs. 3 and 4. A pair of biasing springs 22 and 23 are compressed against the intermediate portions of the jaws l9 and by the bolt 24 which extends loosely through an enlarged opening in each jaw. The bolt 24 is threaded at one end to receive a nut 25 by which the tension of the springs 22 and 23 may be adjusted to provide a predetermined resilient tension on the jaws. justed to grip the rail l5 with any desired pressure, I find it preferable to supply suflicient pressure to resist movement along the mil with .a force of, say, 100 pounds. A similar pair .of Jews are mounted on the guide rail IS.

A pivotal bearing 21 is provided on the end of each rail-gripping jaw remote from the rail. From each pivotal bearing 21 is suspended a braking element comprising a link arm '28 having abrake shoe or roller 29 journaled at its lower end (Fig. l).

A socket 3| is provided in the upper surface of eachjaw for receiving a fiber bumper plug 32 which may be adjusted vertically by a suitable screw bolt 33 extending upwardly through the bottom of the socket (Fig. l). A look nut is provided on each screw bolt so that a predetermined adjustment of the bumper plugs 32 may be permanently maintained.

The rail-clamping jaws are clamped on the rails adjacent to the compensating sheave in such position that their inwardly projecting ends extend through openings 34 in the side plates 1 and 8 and the suspended links 28 and rollers 29 hang adjacent to opposite sides of the associated guide rail, with the tires of the rollers facing the guide rails. The openings .34 should be large. enough to permit the sheave frame to move up or down freely for a short distance without knocking against the rail-clamping jaws.

As illustrated in Fig. 1, a brake-operating lever arm 35 is pivotally suspended from a pivot pin 36 mounted in the side of the plate I so as to swing downwardly adjacent to the left-hand side .of the guide rail l5. A stop lug 31 is mounted on the plate 1 in position to be engaged by a shoulder 38 on the lower end of the arm 35. The lug-should be so placed that it will limit the movement of the lower end of the lever inwardly toward the guide rail 15 but will permit it to move away from the rail.

A compression spring 40 is mounted between a cup 4| formed on the lower end of the lever arm and a spring cup 42 mountedon the inner end of a stud bolt 43, the body of which passes loosely through a boss 44 disposed on the frame plate 1. A pair of screw-threaded nuts 45 and 46 are mounted on the bolt 43 at opposite sides of the 113055 44 so that the amount of compression in the .spring '40 may be adjusted to exert a predetermined pressure biasing the lever arm 35 against the stop lug 31. A similar lever arm 35a and spring 40a. are mounted on the opposite side of the guide .rail l5. Sinnlar lever arms and springs v Although the jaws may be ad- .shoes 14 .on the side plates.

play area.

a given amount and hold them in braking position against the rail 15, under the pressure of the springs 40 and 40a.

In order to adjust the compensating sheave for proper operation, the bolts 24 are loosened suiiiciently to release the clamping springs 22 and 23 sufficiently to permit sliding the jaws and the rollers 29 along the guide rails until the rollers are in proper braking position with reference to the lever arms 35 and 35a. With the gripping jaws in these positions, each of the four bumper plugs 32 should be adjusted to obtain a clearance of :about'2- /2 inches between the upper ends of the bumper plugs and the guiding shoes l4. The

jaws are now moved upwardly along the rails .until1the bumper plugs 32 are nearly in contact with the lower edges of the guide shoes l4 on the side 'plates '1 and. 8. In this position, the bolt 24 is tightened sufficiently to compress the springs 22 and23 to clamp the jaws l9 and 20 to the rails with the desired amount of pressure. This pressure :should be of such a value that it will hold therjawsin position on the :rails but at'the same time low enough to be overcome by the weight of thesheave and its frame when they rest upon the jaws.

:It will be apparent that, when properly adjusted-as above set forth, my improved compensating sheave is normally free to move up and down a predetermined distance.

When the sheave :and its frame are lowered beyond the predetermined distance allotted for free play by expansionor stretching of the compensating :cables or the car cables, the bumper :plugs are engaged by the .lower edges of theguide Inasmuch as the weight of the compensating sheave structure is greater than the slippage resistance of the jaws amount of free play for the sheave and frame.

The compensating sheave, being thus automati- .callyreadjusted for cable stretching, will always gpermitfiree :vertical movement through a predetermined distance.

It-will also be evident that when the elevator car decelerates at ;a :greater rate than the counterweight because ;of an application of the safety :devices or some other reason, a force will be created which may raise the :compensator sheave and its frame above the upper limit of its free .Assuming that this happens, it will 'be apparentit-hat the excessive upward movement of the sheave vwill carry the brake operating arms 35 and 335a1upwardly. When the arms 35 and 35a reach the upper free play limit, they will engage the rollers 29 and wedge them against the rails 15 and Hi. This action will cause a slight retarding of the sheave unit until the rollers reach the cups 48 and 49. At this point, a larger retarding force on the sheave unit will be applied by the compression springs 40 and 43a which will be sufficientto prevent slacking of the elevator lifting cables .under the maximum braking effort of the elevator-safety application. If a greater force 'yet tends to lift the sheave unit it will overcome the predetermined friction between the rollers 29 and the rails .15 and [LB and then the rollers will slide upwardly along the rails, thus preventing breaking the elevator cables due to excessive stress, but yiel'dingly resisting the continued up- Ward travel of the sheave unit beyond the upper limit of its normal free play position. The brak ing friction between the rollers and the guide rails will be determined by adjusting the bolts 43 to compress the springs to a point where they will give such predetermined braking friction as is desired.

In another case the car may be stopped against its bumper in the pit, and the counterweight tend to continue its upward movement. Again the compensating unit will be moved upwardly, and, when its movement extends beyond its normal upper free play limit, the compensating sheave will be clamped to its rails to prevent the lift cables from slackening. As the car cannot go lower, a considerable strain will be placed on the compensating cables. If they are stressed beyond a predetermined limit which, if exceeded, would probably damage them, the force transmitted to the compensating sheave will cause it to slide along its rails retarded by a friction determined by the springs and 400,. Thus the maximum retardation will be applied to the counters and damage to the cables will be prevented.

By the foregoing construction, it will be seen that I have provided a compensating sheave mechanism which will permit a predetermined upward movement of the compensating sheave but which will apply a braking action of a predetermined value when the compensating sheave unit exceeds its predetermined free upward movement.

Although I have illustrated and described only one specific form of my invention, it is to be understood that changes therein and modifications thereof may be made without departing from its spirit and scope.

I claim as my invention:

1. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame supported by said sheave, vertical guide rails for guiding the frame, a plurality of braking rollers, friction clamping means disposed on the guide rails for supporting said braking rollers, means responsive to downward movement of the frame for moving the friction clamping means downwardly on the guide rails, means on said frame for causing the braking rollers to apply a predetermined braking force to the frame when it is lifted by the cables, and spring means for limiting the braking force.

2. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame comprising a pair of side plates secured together in enclosing relation around said sheave, a shaft for rotatively supporting said sheave in said frame, guide shoes on the frame extending in operable relation to the guide rails, resilient clamping devices secured to each guide rail, braking elements associated therewith, brake operating arms pivotally mounted on the frame for engaging said braking elements to apply a braking force to the frame when it is lifted by the compensating cable, and spring means mounted between the frame and the arms for limiting the braking effect to a predetermined value.

3. A compensating sheave mechanism for elevators comprising a frame, a plurality of guide shoes on the frame for engaging a pair of guide rails, a cable receiving sheave rotatably mounted on the frame, a plurality of devices for slidably and frictionally engaging the guide rails to limit free vertical movement of the sheave to a predetermined distance, a plurality of braking devices cooperatively mounted on the frame and the slidable devices for applying a braking effect to the frame when it moves beyond a predetermined distance, and adjustable devices mounted on the frame for limiting the braking effect of the braking devices to a predetermined value.

4. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame, means for rotatably mounting the sheave in the frame, a pair of vertical guide rails, a plurality of guide shoes on the frame for guiding it along the guide rails, resilient clamping means disposed on each guide rail, braking elements attached to the clamping means, brake-operating arms mounted on the frame and responsive to a predetermined vertical movement of the frame for moving the braking elements into braking engagement with the guide rails, and adjustable devices disposed on the frame for applying a predetermined pressure to the brake-operating arms for controlling the braking effect to a predetermined value.

5. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame supported by said sheave, vertical guide rails for guiding the weight frame, a plurality of braking elements, clamping devices disposed on the guide rails for supporting said braking elements, a plurality of braking arms pivotally mounted on the frame for causing the braking elements to apply a braking force to the frame when it is lifted by the cables beyond a predetermined distance, a plurality of stop members disposed on the frame for limiting movement of the braking arms toward the guide rails, a plurality of springs for biasing the braking arms toward the stop members, and adjustable devices for controlling the biasing pressure of the springs on the braking arms whereby the braking effect of the frame may be controlled to a predetermined value.

6. A device for tensioning and guiding elevator compensating cables comprising a cable receiving sheave, a weight frame mounted on the sheave, a pair of vertical guide rails disposed beside the frame, a plurality of guide shoes disposed on the frame for engaging the guide rails to guide the sheave unit in its vertical movements, clamping devices mounted on the rails, braking shoes suspended from the clamping devices and disposed adjacent to the sides of the rails, a plurality of brake-operating arms having their upper ends pivotally attached to the frame and their lower ends provided with curved recess portions disposed to nest the brake shoes when the frame moves upwardly beyond a predetermined point, a plurality of stop members disposed on the frame for limiting the movement of the brake-operating arms toward the guide rails, springs for biasing the brake-operating arms toward the stop members, and adjustable means for controlling the biasing pressure of the springs on the brake-operating arms whereby the braking effect may be controlled to a predetermined value.

EDGAR M. BOUTON. 

